fMRI studies of media use
fMRI studies during and after screen media exposure reveal pronounced and specific activation patterns. Viewing nonviolent television programs activates brain regions associated with visual and auditory processing. Viewing violent programs activates areas associated with negative affect, including the right amygdala, posterior cingulate, inferior parietal, premotor cortex, hippocampus and parahippocampus bilaterally, and dorsal anterior cingulate cortex.1,2
One study of “gamers” who played over 20 hours a week showed increased glucose metabolism in the right orbitofrontal gyrus, left caudate, and right insula after play. Decreased metabolism was seen in the bilateral postcentral gyrus and bilateral occipital regions while at rest. These patterns were similar to those seen in drug addicts. Park and colleagues3 suggest that online gaming may be addictive to the genetically vulnerable. This is consistent with the repeated finding in studies of violent media: subjects tend to divide into those for whom violent stimuli are exciting and pleasurable and those for whom it is neutral or aversive. More males than females fall in the former category.4
Unlike drugs or toxins, there is no evidence that screen media alone are lethal in overdose; however, media clearly change behavior, and many people are unable to relinquish their use despite negative consequences. For example, texting while driving increases the risk of crashing or near-crashing by a factor of 23; nevertheless, the practice continues to flourish.5 One survey found that 1 in 8 US adults is addicted to the Internet.6
The general rules of toxicology are that outcome depends on dose, potency (or in this case, content), route of exposure, developmental window of vulnerability, and constitutional and environmental risk modifiers. Another principle is that of hormesis: a small exposure may be beneficial through cellular adaptation that confers protection or even adaptive resilience. Screen media may be harmless or they may foster positive adaptation when used in appropriate doses by people of certain ages. However, as the dose increases, and during vulnerable developmental windows, negative effects overwhelm protective capacities and cause harm.
CHECKPOINTS
■ Screen media present highly arousing, abnormal sensory input to the brain’s activating system. Downstream effects of arousal include the release of catecholamines, increased vigilance and irritability, motor behavior problems, a decreased attention span, and sleep problems.
■ One study showed that those who play video games for more than 20 hours a week have an increase in glucose metabolism in the right orbitofrontal gyrus, left caudate, and right insula after play, and a decrease in metabolism in the bilateral postcentral gyrus and bilateral occipital regions while at rest. This pattern is similar to that seen in drug addicts.
■ Overall, initial exposure to media with violent content increases short-term aggression, especially in younger children and boys. While early, excessive exposure to media statistically and independently increases the likelihood of later antisocial behavior in populations, this is not necessarily the case in individual children.
■ The risk of receiving an attention-deficit/hyperactivity disorder diagnosis at age 7 increased with every hour of television watched at 1 and 3 years.
Violent media and violence
It is difficult to link screen media in isolation to larger, social changes, such as increases in violence. These downstream, complex events are the cumulative results of multiple factors.7 Children’s heavy exposure generally co-occurs with low parental monitoring and heavy overall viewing.8 However, population studies of isolated cultures after the introduction of media show an initial increase in youth aggression.1 Overall, initial exposure to media with violent content increases short-term aggression, especially in younger children and boys. Moreover, early, excessive exposure to media statistically and independently increases the likelihood of later antisocial behavior in populations.9 As with most exposures, environmental and constitutional factors interact with media exposure to produce given outcomes.
Screen media effects on children
Prospective studies have causally linked media excess in young children with impulsive and aggressive behavior, obesity, and delayed development of language and reading skills.10-12 A recent, large longitudinal study replicated and expanded previous findings that attentional problems associated with increased video game and screen media use persisted into adolescence.13
Keeping our toxicology model in mind, let’s do a quick survey of the impact on the brain by developmental stage.
Babies through preschool. During the first 5 years of life, when the neurological foundations of learning and emotion regulation are being laid down, screen media appear to be most detrimental. Television for babies interrupts play, is not educational, diminishes time spent with family members, and interferes with sleep.14 Sesame Street and Teletubbies have been found to have a negative impact on vocabulary.14 The American Academy of Pediatrics recommends no screen use by children younger than 2 years.15 In fact, the average baby in the United States is exposed to 2 hours of screen media daily, and 65% of children up to age 6 have a television on half the time.16 In the average US home, the television is on 8 hours a day.17 By 3 months of age, 40% of children are exposed to screen media, and by 24 months, the percentage rises to 90%. Exposure rises from an hour a day for infants to over 1.5 hours a day by age 2.18
I don’t like television myself. I suppose it’s all right in small doses, but children never seem to be able to take it in small doses. —Willie Wonka.
Charlie and the Chocolate Factory The dose makes the poison. —Paracelsus
One large study demonstrated that the risk of receiving a diagnosis of attention-deficit/hyperactivity disorder at age 7 increased with every hour of television watched at 1 and 3 years, after adjusting for variables such as maternal function and the quality of home life.10 When the television is on, there are significantly fewer vocalizations between adults and babies, which may explain the finding that children who watch a lot of television before kindergarten are delayed readers and are at increased risk for learning disabilities.12,19
Screen media affect not only children but adults as well. Parents become less adept at interacting with their youngsters as they carry on their own, adult functions of running a home. Media can disrupt the normal, attuned parent-child feedback that is the foundation of emotional regulation. This implies that while heavy media use tends to co-occur with other aspects of family dysfunction, it also appears to be an independent toxic agent.
